Search for Lepton Flavour Violation at HERA

TL;DR

This paper reports a search for lepton flavour violating leptoquarks at HERA, finding no evidence and setting mass exclusion limits up to 712 GeV for muon-quark and 479 GeV for tau-quark couplings.

Contribution

First search for second and third generation leptoquarks via lepton flavour violation at HERA with comprehensive data analysis.

Findings

No evidence for leptoquark production observed.

Excluded leptoquark masses up to 712 GeV for muon-quark couplings.

Excluded leptoquark masses up to 479 GeV for tau-quark couplings.

Abstract

A search for second and third generation scalar and vector leptoquarks produced in ep collisions via the lepton flavour violating processes ep -> mu X and ep -> tau X is performed by the H1 experiment at HERA. The full data sample taken at a centre-of-mass energy sqrt{s} = 319 GeV is used for the analysis, corresponding to an integrated luminosity of 245 pb^-1 of e^+ p and 166 pb^-1 of e^- p collision data. No evidence for the production of such leptoquarks is observed in the H1 data. Leptoquarks produced in e^+- p collisions with a coupling strength of lambda=0.3 and decaying with the same coupling strength to a muon-quark pair or a tau-quark pair are excluded at 95% confidence level up to leptoquark masses of 712 GeV and 479 GeV, respectively.